System and method for enhanced argon recovery from a feed stream comprising hydrogen, methane, nitrogen and argon
AssigneePraxair Technology, Inc.
InventorHenry E. Howard
Life of this patent
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Abstract
A system and method for argon and nitrogen extraction from a feed stream comprising hydrogen, methane, nitrogen and argon, such as tail gas of an ammonia production plant is provided. The disclosed system and method provides for nitrogen-argon rectification and the methane rejection within a column system comprised of at least one distillation column. Nitrogen and argon are further separated and to produce liquid products. An argon stripping column arrangement is disclosed where residual argon is further removed from the methane-rich fuel gas and recycled back to the feed stream.
Claims22
A method for separating a feed stream comprised primarily of hydrogen, nitrogen, methane and argon, the method comprising the steps of:
- conditioning the feed stream to a temperature suitable for distillation at pressure less than 400 psia;
- directing the conditioned feed stream to a rectification system which is comprised of at least one rectifying column;
- separating the conditioned feed stream in the rectification system to produce an argon depleted nitrogen enriched vapor stream, an argon enriched stream, and a methane-rich liquid stream;
- directing the methane rich liquid stream into an argon stripping column configured to strip argon from the methane rich liquid stream using an argon-depleted, nitrogen rich vapor stream having an argon concentration less than the argon concentration of the methane-rich liquid stream;
- directing the argon-depleted, nitrogen rich vapor stream into the argon stripping column at a feed point below a feed point of the methane rich liquid stream such that mass transfer of argon is effected between the methane rich liquid stream and the argon-depleted, nitrogen rich vapor stream;
- extracting an argon depleted methane rich liquid from the bottom of the argon stripping column;
- extracting an argon containing overhead gas from the top of the argon stripping column;
- and
- recovering purified argon from the argon containing overhead gas or recycling the argon containing overhead gas to be recombined with the feed stream.
A system for separating a feed stream comprising hydrogen, nitrogen, methane and argon, the system comprising:
- a conditioning circuit configured for conditioning the feed stream gas to a temperature suitable for rectification and at pressure less than or equal to about 400 psia;
- at least one rectifying column configured to receive the conditioned feed stream and produce an argon depleted, nitrogen rich vapor stream, an argon enriched stream, and a methane-rich liquid stream;
- an argon stripping column configured to receive the methane rich liquid stream and strip argon from the methane rich liquid stream using the argon depleted, nitrogen rich vapor stream and produce an argon depleted methane rich liquid from the bottom of the argon stripping column and an argon containing overhead gas from the top of the argon stripping column;
- and
- a recycle circuit configured for extracting the argon containing overhead gas from the argon stripping column and mixing the argon containing overhead gas with the feed stream;
- an auxiliary rectification column configured to rectify the argon enriched stream to produce a high purity argon stream and a high purity nitrogen stream.
Dependencies are inferred from the claim text.